Directional antenna array



Jan. 7,-1941. E. WERNDL DIRECTIONAL ANTENNA ARRAY Fil'ed Aug. 8, 1959 2 Sheets-Sheet l Hews/m can 77601 Isnuoutot EH7 J Z We 2'27 0 Cittorneg Jan. 7, 1941.

E. WERNDL DIRECTIONAL ANTENNA ARRAY 2 Sheet I I llhgnf v /76f p 07 v G me! v Filed Aug. 8, 1959 Patented Jan. 7, 1941 UNITED STATES PATENT OFFICE DIRECTION ALAN TENNA ARRAY many Application August 8, 1939, Serial No. 289,077 In Germany August 11, 1938 6 Claims.

This invention relates to directional antenna arrays and especially to a plurality of arrays which are separately rotated andsimultaneously phased to maintain their combined pattern in any desired direction.

In direction finders operating with loop or other antennas of small dimensions, owing to the dimensions of the antenna the receiving energy is limited and thus often insuflicient for direction finding at substantial distances. This drawback can be overcome by operating with a larger number of such receiving antennas. Eventually, still further advantages may hereby be obtained such as an improved characteristic of the entire system, or an increased sharpness of the indication.

In such cases, especially when operating on relatively short waves, it is material how the received energies are combined, since they are applied to a common receiver. While all antennas situated side by side in the direction of the wavefront have the same phase, antennas which are arranged in back of each other in the direction of the ray have phase displacements and have the same phase only when spaced at a distance equal to A. It is old to provide phase control means in the leads of the individual antenna structures by means of which the phase can be properly set and adapted to the respective operating conditions. However, all phase displacements change if, in order to find a new direction, the antennas are each turned separately, although they remain parallel to one another.

The object of the present invention is to provide an arrangement in which the phases once set for a certain direction of reception are maintained automatically substantially correct also for other directions of reception when turning the receiving antennas and whereby the influencing of the elevation angle and the width of the characteristic can be uniformly assured in a simple manner.

The invention will be described by reference to the accompanying drawingsin which Figure 1 is a schematic diagram of one embodiment of the 5 invention; Figure 2 is a perspective view of an element of the invention; and Figure 3 is a view partly in perspective of an arrangement of the invention.

There is shown schematically in Fig. 1 an array 50 of antennas al, a2, a3, etc., having a directional pattern in one or two directions and connected with a common receiver E by means of shielded leads bl, b2, b3, etc., and across phase control means cl, c2, c3, etc. This may be done as is 55 known with the interposition of afrequency transformation or any suitable type of phase shifter;

' for example, that disclosed in the copending application Serial No. 131,838, filed March 19, 1937, entitled Apparatus for measuring phase angle. Furthermore, a mechanical or electromechani- 5' cal drive through which all antennas remain parallel and are turned into the desired direction may be considered present as shown in Fig. 3, although not shown in Fig. 1, to avoid complexity.

Fig. 1 illustrates that, in the position of the 10 directional antennas represented by the solid line arrows, the antennas a2, a5, a8 and a3, a6, a9 respectively oscillate in different phases with respect to a wave from the direction RI, whereas, for instance, the antennas a2, a1 and a5, al 0, etc., 15' operate in equal phase. However, in another case, for the direction R2, the antennas will have the position shown in dash lines and other phase conditions will prevail, i. e., the series al, a2, all then a4, a5, a6 and then a8, 0.9, all! have the 20 same phase as regards the individual antennas but phases of different values as regards the series. Hence, there exists a functional relationship between the individual phase angles and the respective angle of the direction. Moreover, this 25 condition will change when tuning to different wave lengths and further depends on the elevation angle of the wave beam.

The described functional dependence can be resolved in a purely mechanical fashion and in 30 a simple manner as will be described so that when taking bearings all phase relations will be controlled simultaneously with a change of direction. This can be achieved through a single setting for a change of direction and also for 35 tuning to different wave lengths and for adjusting to the elevation angle. The individual phase shifting means cl, 02, etc., to this end are so arranged according to Fig. 2 that in each of them the phase will be controlled by the vertical move- 40 ment of a rod l actuated as a function of the ordinates of an oblique plane 01 below them. According to Fig. 3, the phase shift means cl, c2, 03, etc., are disposed in the same plane adjacent one another and, for instance, in the same manner as the antennas in the outer field which are assigned to said means. The control rods l, 2, 3, etc., rest on the oblique plane d. The degree of the inclination of this oblique plane, which can be set by swinging about a horizontal axis xx, determines the difierences of the individual phase angles, namely, in the direction of the obliquity of the plane, whilst phase shift means situated in the direction war have respective phase equality. However, if the oblique plane at is turned about a vertical axis yy synchronously with the antennas when taking bearing by means of any suitable like mechanism e or synchronized motors, then (at proper matching of the electrical and mechancal values) the phases in the individual antenas just follow those laws which correspond to the maintenance of the correct conditions at each bearing angle position. The tuning to another wave length and the correction necessary when changing the elevation angle take place likewise in common for all antennas by a simple change of the inclination of the oblique plane and remain also invariably correct for all bearing angles.

The mechanical structure is not limited to the example of construction shown. More especially, the oblique plane may be replaced by other guide devices which operate by individual action or automatically, or any desired mechanical hydraulic, or electromechanical transmission members may be interposed between such device and theindividual phase shifting means. The invention not only relates to direction finders but can also be applied to the directed radiation of waves.

I claim as my invention:

1. A directional antenna array including a plurality of directional antennas, means for rotating each of said antennas about a difierent center, phasing means connected to each antenna for obtaining a desired combined pattern of said array, and means for adjusting said phasing means connected to each of said antennas as each of said antennas is rotated so that said combined pattern may be substantially maintained.

2. A directional antenna array including a plurality of antennas each having directional patterns in a horizontal plane, phasing means for connecting said antennas to a common circuit in a desired phasal relation, means for rotating each of said antennas about different centers, and means operated in synchronism with said rotational means for adjusting each of said phasing means connected to each of said antennas so that said desired phasal relation is maintained independent of the position of each of said antennas.

3. In an array of the character of claim 1, means for adjusting simultaneously said phasing means as a function of frequency so that the desired pattern may be obtained for waves of different frequencies.

4. In an array of the character of claim 1, means for adjusting simultaneously said phasing means as a function of angle of elevation of said array so that the desired pattern may be obtained for difierent angles of elevation.

5. In an array of the character of claim 1, a rotatable inclined plane arranged to actuate said phasing means as a function of the angular position of said antennas, said plane being coupled to the means for rotating said antennas so that said plane and said antennas are rotated synchronously.

6. In an array of the character of claim 1, a rotatable inclined plane arranged to actuate said phasing means as a function of the angular position of said antenna and'having its angle of incline adjustable to maintain the desired phase relations over a range of frequencies, said plane being coupled to the means for rotating said antennas so that said plane and said antennas are rotated synchronously.

ERNST WERNDL. 

